Survival Analysis for the Productive Life of Commercial Sows

A stratified survival analysis was compared with a non-stratified model to identify significant factors affecting the productive life of commercial sows and to estimate the heritability for sow productive life. Data for 3,074 sows were used for the survival analysis under a Cox model. The stratified model identified factors associated with sow survival that were not statistically significant in an unstratified model. High average daily feed intake and low feed conversion ratio reduced the risk of culling (solutions: -0.35 and 0.30) prior to herd entry; higher total born in parity one reduced the culling risk (solution: -0.032) prior to the second farrowing; and higher fat levels, treated as a time dependent covariable, reduced risk (solution: -0.026) of culling throughout the sows lifetime. After accounting for risk factors, the heritability for survival on the underlying scale was 0.04±0.001, demonstrating that the heritable component for survival is not solely attributable to the influences of other heritable traits.